1. Field of the Invention
The present invention relates to a connector for making a structural connection between a plurality of structural members joined at an angle. Specifically, the present invention relates to a self-adjusting heel joint connector for securing a roof rafter, ceiling joists/ties, and supporting walls, without the need for a conventional birdsmouth cut. The connector includes a swivel joint to allow for adjustment to a precise preset roof pitch for transferring vertical load through the connector directly to the top of the supporting wall plate and has the capability of transferring rafter thrust force to the joist/tie member. The framing member of the connector may further act as a guide for proper fastener placement to transfer rafter thrust force to the joist/tie member. The design of the present invention forms a stable unit which provides greater lateral structural stability, while saving construction time and costs.
2. Description of Related Art
Light frame building construction is the predominant method of construction in the residential and light commercial construction market. In light frame construction, a birdsmouth joint or cut is a woodworking joint that is generally used to connect a roof rafter to the top plate of a supporting wall. It is an indentation cut into the rafter which consists of a “seat cut” (the face of which rests on the top plate) and a “heel cut” or “plumb cut” (the face of which lies parallel to the supporting wall), forming a shape resembling a bird's mouth. The indentation should not extend unsupported on the interior in order to maintain the structural integrity of the rafter because the unsupported section can split along the grain of the wood. Saw blade overrun at the birdsmouth cut can also cause damage to the rafter. The depth of a rafter cut varies according to the desired roof pitch.
The “heel” joint is generally fastened with nails by toe-nailing the rafter from the side into the top plate below. Toe-nailing of the rafter to the wall plate often also leads to splitting of the rafter.
Many different connectors are used in the art for joining structural members for building construction, and these different connectors are designed to secure rafters to the adjoining wall of a building structure, often at a unique angle of attachment. The connectors are typically provided with through-holes for fasteners to be driven through the connector and into the side faces of the structural members being connected. In addition, other connectors for securing a rafter to a supporting wall must be designed for withstanding upward and lateral loads developed by high winds, which can differ by geographic location, and may include hurricane forces.
The prior art has provided numerous configured connectors to secure structural members to one another, particularly in the area of rafter-joist-wall attachments; however, each has various disadvantages which impede the connector's effectiveness.
For example, U.S. Pat. No. 2,354,801 issued to De Huff on Aug. 1, 1944, entitled “RAFTER SEAT”, discloses a rafter seat comprising a sheet of metal bent to form a pair of horizontally disposed spaced base plate portions for seating on the upper face of a plate structure or the like; a rafter seat portion forming a joist supporting flat surface inclined with relation to said base plate portions; and a pair of vertically extending intermediate wall portions connecting said seat portion to the respective plate portions.
De Huff's connector must be in place at the heel joint prior to placing the rafter, and therefore cannot adjust to accommodate a preset roof pitch. Further, the sloping surface is an integral part of the connector and a separate connector would have to be made for each different roof pitch. The connector also does not allow for direct full surface contact between the bottom of the rafter and the top of the supporting wall plate. There appears to be no provision for transferring rafter thrust force directly to the adjacent joist/tie to complete the structural system.
In U.S. Pat. No. 2,477,163 issued to Barnett on Jul. 26, 1949, entitled “TRUSS SHOE”, a truss shoe for use with a joist and a rafter having an end face and a bottom face resting on said joist comprising a pair of parallel, spaced apart, elongated side plates of L shape and having vertical and horizontal portions and of sufficient extent to overlie parts of the side faces of said joist and said rafter; a horizontal saddle plate connecting upper edges of the horizontal portion of the side plates and extending therebetween to overlie the upper face of the joist; a second horizontal saddle plate connecting the side plates at the other end thereof and extending therebetween to overlie the upper face of the joist and coplanar with the first mentioned saddle plate; and a vertically disposed plate adjacent and above the second saddle plate and extending between and connecting the side plates to function as an abutment for the end face of the rafter, is taught.
The truss shoes may be applied and secured to opposite ends of the joist by bolts or nailing, and thereafter the rafters may be placed in position and secured by nailing to the joists. Alternatively, the truss shoes and rafters may all be assembled on the ground and then hoisted up and placed in position on the wall plates.
Barnett's design includes no lateral bracing to the wall and no connection to the wall plate, and is primarily made for a truss connection. As shown, the rafter is directly over the joist. The rafter pitch must be predetermined prior to truss fabrication, and there is no capability to adjust rafter pitch.
In U.S. Pat. No. 3,967,908 issued to Snow et al. on Jul. 6, 1976, entitled “CROSS TIE SADDLE BRACKET”, a weld fabricated steel saddle bracket having an elongated angle member with a portion thereof adapted to abut the side of the top wall plate of a building and another portion thereof adapted to lie on the top of the top wall plate and two identical right angle members having horizontal portions welded to the top portion of the elongated angle member so that the side edges thereof are in planar alignment with the side portion of the elongated member and the ends thereof lie flush with the ends of the elongated member, and the two identical right angle members having vertical portions projecting upwardly in parallel spaced apart relationship from the top surface of the top wall plate to form a saddle to receive the cross tie members and roof rafters of the building, is taught.
Snow's connector is a welded connector having no adjustable seat, and the rafter must be cut for a seat to adjust the roof pitch. There is also no provision for transferring rafter thrust force to an adjacent joist/tie member.
In U.S. Pat. No. 5,230,198 issued to Callies on Jul. 27, 1993, entitled “VARIABLE PITCH CONNECTOR”, a connector for connecting a bearing member, having top, bottom, and side faces, with an inclined member having top, bottom and side faces, said connector comprising: a base having a first edge and means for connecting said base to said bearing member; a cradle member having a connection end, a free end, a bottom and a pair of sides extending upwardly at right angles from said bottom and configured to receive said inclined member, said cradle member being integrally connected at said connection end to said base along said first edge and including means for connecting said cradle to said inclined member; and a separate support member, connected to said base for supporting said cradle member, is taught.
Callies' connector must be in place prior to placing the rafter, and requires hammering to force the connector to adjust its riser seat for required pitch. Further, the connection is field bent during hammering. Callies' connector includes a separate support member which is hammered between the cradle member and the top of the supporting wall plate to adjust the pitch of the cradle member. This support member is wider than the cradle member and therefore projects on both sides of the rafter, prohibiting flush contact with an adjacent joist/tie member. Moreover, the cradle member sides also prohibit the rafter from being flush with the joist/ties, which prevents the proper fastening needed to transfer the rafter thrust load to the joist/ties. In addition, one end of the cradle member supporting the inclined member bears on the line edge of the wall plate. Building code requirements are that the load be transferred to the top of the wall plate for a minimum of 1½″ bearing, which is not possible with Callies' connector.
In U.S. Pat. No. 5,335,469, issued to Stuart on Aug. 9, 1994, entitled “RAFTER TO PLATE CONNECTION”, a rafter to plate connection in a wood frame building including wood top plate, and a wood rafter joined by a variable pitch connector including a rafter seat for receiving a portion of the wood rafter, a fixed base member affixed to the outside edge of the wood top plate, first and second side members joined to opposite sides of the wood rafter, and an adjustable base member joined to the rafter seat along a bend line and having a lower end in contact with the upper surface of the wood top plate, is taught. Fasteners join the fixed base member to the outside edge of the wood top plate, the adjustable base member to the wood top plate and the wood rafter to the side members.
Similar to Callies' connector, Stuart's connector must be in place prior to placing the rafter, and requires hammering to force the connector to adjust its riser seat for required pitch. Further, the connection is field bent during hammering. As in Callies, the connector first and second side members prohibit the rafter from being flush with the joist/ties, which prevents the proper fastening needed to transfer the rafter thrust load to the joist/ties. One end of the rafter seat bears on the line edge of the wall plate, which does not allow for transfer of the vertical load directly to the top of the wall plate.
The present invention overcomes the disadvantages of the prior art by providing a heel joint connector that is self-adjusting to accommodate preset rafter pitches and provides for a code-required minimum of 1½″ bearing between the bottom of the rafter and the top of the supporting wall plate, while transferring vertical load through the connector directly to the top of the supporting wall plate and transferring rafter thrust force to the adjacent joist/tie member, completing the structural system. Further, the framing member of the connector can be used as a guide by a craftsman in the field for proper placement of fasteners to transfer rafter thrust force to an adjacent joist/tie member.
Other advantages of the present invention include a reduction in the time required to fabricate each rafter, including but not limited to, handling, measuring, layout and omitting a birdsmouth cut in the rafter, as well as eliminating the need for conventional toe-nailing of the rafter to the supporting wall plate and field metal bending.